Piezo Positioning Actuator Resonance Monitoring for Defect Detection
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Solution Overview
Problem
Piezoelectrically driven positioning devices suffer from mechanical stress leading to defects such as microcracks and delaminations, which can cause sudden failure, necessitating a method for early detection and prevention of such defects.
Innovation Solution
A positioning device incorporating a piezoelectric actuator that functions as both a generator and receiver of acoustic ultrasonic waves, utilizing a defect analysis device to compare resonance patterns before and during operation, enabling detection of emerging or changed resonances to predict and prevent component failure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If piezoelectric actuators are used for fine positioning, then positioning precision is improved, but reliability deteriorates due to mechanical stress and defect development
Solution Approach 1:
The patent applies preliminary action by continuously monitoring the resonance pattern of the actuator before defects cause total failure. The system detects changes in resonance frequency and damping ratio that indicate developing defects, allowing preventive maintenance to be performed before the actuator fails completely, thus resolving the contradiction between using high-precision piezoelectric actuators and maintaining their reliability
Solution Approach 2:
The patent implements feedback by using the actuator itself as both a driver and a sensor. The resonance characteristics of the actuator are continuously measured and fed back to the control system, which can detect defect development and adjust operation accordingly. This feedback mechanism allows the system to maintain reliability while using high-precision piezoelectric actuators
2Measurement precision
If additional transmitters and receivers are installed for defect detection, then measurement capability is improved, but device complexity increases
Solution Approach 1:
The patent applies universality by making the piezoelectric actuator multi-functional. The same actuator that provides positioning functionality also serves as the transmitter and receiver for ultrasonic defect detection. By exciting the actuator at its resonance frequency and measuring its mechanical response, the system can detect defects without adding separate transmitters and receivers, thus improving measurement capability while avoiding increased device complexity
Solution Approach 2:
The patent merges the positioning function and the defect detection function into a single integrated system. The actuator's mechanical vibrations used for positioning are also utilized for ultrasonic testing, combining two functions into one component and eliminating the need for additional separate systems
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enables timely detection and prevention of defects, reducing the risk of total failure and eliminating the need for additional transmitters and receivers, thus enhancing reliability and reducing maintenance costs.
Implementation Method 1
Piezoelectric actuators are electromechanical energy converters whose operating principle is based on the deformation of certain crystals under the influence of an electric field
Implementation Method 2
the positioning unit has a single actuator, which comprises a generator and a receiver of acoustic ultrasonic waves
Implementation Method 3
Every mechanical system exhibits a specific resonance pattern, which depends on the shape, geometric dimensions, material properties, etc., of individual system components. Defects cause a change in a system's resonance pattern.
Data Source
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Figure 3a~3d
AI summary
The invention relates to a positioning device (1) comprising a positioning unit (2) having at least one piezoelectric actuator (4), a drive element (5) to be coupled with an element (6) to be positioned, and a controller (3). The positioning device has a defect analysis device (16) for detecting defects in the positioning unit (2), wherein the actuator (4) or actuators, in addition to functioning as a drive for the drive element (5), functions or function as a generator (12) or a receiver (13) of ultrasonic sound waves, and the defect analysis device (16) comprises a measurement signal generator (22) for generating a sinusoidal electrical voltage for exciting the or a generator (12) and a resonance analyser (24) for analysing an electrical signal generated by the or a receiver (13). The invention also relates to a method for operating such a positioning device in order to detect defects in the positioning unit (2).